This invention relates to a pipe coupling of the type comprising an elastomer sealing sleeve which is approximately C-shaped in cross-section and which defines sealing lips which extend toward each other and are each supported on a sleeve web by means of an annular bead; a housing which surrounds the sleeve and defines radial end walls and a longitudinal gap; a closure which comprises tensioning bolts operative to constrict the housing; and an insert sheet which is inserted between the sleeve and the housing and bridges the longitudinal gap; wherein the sealing lips of the seal define first, larger dimensions before the housing is constricted; and wherein it is possible for the sealing lips to be compressed in the circumferential direction and to be pressed snugly onto a pipe wall due to compression of the annular beads as the housing is constricted.
Pipe couplings of this type, as shown, for example, in German Patent Specification 2,428,101 and corresponding U.S. Pat. No. 3,877,733, have revolutionized pipe connection technology. On the one hand, due to the fact that the sealing lips have larger dimensions in relation to the nominal diameter of the pipes to be connected prior to assembly, it is possible for the couplings to be pushed onto the pipes and installed together with the pipes, it being possible for the pipes simply to be placed next to one another and for the couplings then to be pushed over the joints. On the other hand, the compression of the lip seal in the circumferential direction due to the constrictable housing leads to the fact that the radial thickness of the sleeve increases so that the sleeve is not only pressed against the pipe wall by the housing, but the sleeve tends to mold itself to the pipe surface. This results in fully satisfactory sealing, even in the case of a rough or irregular pipe surface, and additionally in a sealing capability which remains intact for a long time.
The object of the present invention is to improve the known pipe coupling in such a way that the constrictability of the housing is utilized for increasing the insensitivity of the coupling with regard to changes due to expansion, especially when the coupling is pressure less.